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        <h3 id="Hystrix简单使用、降级、熔断、请求缓存、请求合并示例"><a href="#Hystrix简单使用、降级、熔断、请求缓存、请求合并示例" class="headerlink" title="Hystrix简单使用、降级、熔断、请求缓存、请求合并示例"></a>Hystrix简单使用、降级、熔断、请求缓存、请求合并示例</h3><a id="more"></a>
<h1 id="一、简单使用"><a href="#一、简单使用" class="headerlink" title="一、简单使用"></a>一、简单使用</h1><ol>
<li>定义command</li>
<li>继承HystrixCommand</li>
<li>指定构造，构造函数需要调用父类构造，并且指定groupKey</li>
<li>在重写的run()方法中编写依赖逻辑</li>
</ol>
<figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br></pre></td><td class="code"><pre><span class="line">public class HelloWorldCommand extends HystrixCommand&lt;String&gt; &#123;</span><br><span class="line"></span><br><span class="line">    private String name;</span><br><span class="line"></span><br><span class="line">    public HelloWorldCommand(String name) &#123;</span><br><span class="line">        // 指定命令组名称</span><br><span class="line">        super(HystrixCommandGroupKey.Factory.asKey(&quot;hello-world&quot;));</span><br><span class="line">        this.name = name;</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    @Override</span><br><span class="line">    protected String run() throws Exception &#123;</span><br><span class="line">        return &quot;Hello &quot; + name + &quot;,current thread:&quot; + Thread.currentThread().getName();</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    public static void main(String[] args) throws InterruptedException, ExecutionException, TimeoutException &#123;</span><br><span class="line">        /**</span><br><span class="line">         * 每个命令对象实例只能调用一次，不能重复调用</span><br><span class="line">         */</span><br><span class="line">        HelloWorldCommand helloWorldCommand = new HelloWorldCommand(&quot;Synchronous-hystrix&quot;);</span><br><span class="line">        // 同步调用，执行run()方法</span><br><span class="line">        String executeResult = helloWorldCommand.execute();</span><br><span class="line">        System.out.println(&quot;HelloWorldCommand ExecuteResult:&quot; + executeResult);</span><br><span class="line"></span><br><span class="line">        helloWorldCommand = new HelloWorldCommand(&quot;Asynchronous-hystrix&quot;);</span><br><span class="line">        // 异步调用</span><br><span class="line">        Future&lt;String&gt; future = helloWorldCommand.queue();</span><br><span class="line">        // 同步阻塞获取结果</span><br><span class="line">        String futureResult = future.get(100, TimeUnit.SECONDS);</span><br><span class="line">        System.out.println(&quot;HelloWorldCommand QueueResult:&quot; + futureResult);</span><br><span class="line"></span><br><span class="line">        System.out.println(&quot;Main Thread:&quot; + Thread.currentThread().getName());</span><br><span class="line">    &#125;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
<h1 id="二、带有降级逻辑"><a href="#二、带有降级逻辑" class="headerlink" title="二、带有降级逻辑"></a>二、带有降级逻辑</h1><ol>
<li>重写父类的getFallback()方法<figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br></pre></td><td class="code"><pre><span class="line">public class FallBackCommand extends HystrixCommand&lt;String&gt; &#123;</span><br><span class="line"></span><br><span class="line">    private String name;</span><br><span class="line"></span><br><span class="line">    public FallBackCommand(String name) &#123;</span><br><span class="line">        /**</span><br><span class="line">         * 配置hystrix执行超时时间为500ms</span><br><span class="line">         */</span><br><span class="line">        super(Setter</span><br><span class="line">                .withGroupKey(HystrixCommandGroupKey.Factory.asKey(&quot;fallback&quot;))</span><br><span class="line">                .andCommandPropertiesDefaults(HystrixCommandProperties.Setter().withExecutionTimeoutInMilliseconds(500))</span><br><span class="line">        );</span><br><span class="line">        this.name = name;</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    @Override</span><br><span class="line">    protected String run() throws Exception &#123;</span><br><span class="line">        Thread.sleep(1000);</span><br><span class="line">        return &quot;Hello &quot; + name + &quot;,current thread:&quot; + Thread.currentThread().getName();</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    @Override</span><br><span class="line">    protected String getFallback() &#123;</span><br><span class="line">        return &quot;服务超时，对服务进行降级&quot;;</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    public static void main(String[] args) &#123;</span><br><span class="line">        FallBackCommand fallBackCommand = new FallBackCommand(&quot;fallback-hystrix&quot;);</span><br><span class="line">        String fallBackResult = fallBackCommand.execute();</span><br><span class="line">        System.out.println(&quot;FallBackCommand FallBackResult：&quot; + fallBackResult);</span><br><span class="line">    &#125;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
</li>
</ol>
<h1 id="三、模拟信号量隔离"><a href="#三、模拟信号量隔离" class="headerlink" title="三、模拟信号量隔离"></a>三、模拟信号量隔离</h1><ol>
<li>同时启动20个线程并发执行</li>
<li>只有10个可以成功执行，另外10个只能走降级逻辑<figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br><span class="line">61</span><br><span class="line">62</span><br><span class="line">63</span><br><span class="line">64</span><br><span class="line">65</span><br><span class="line">66</span><br></pre></td><td class="code"><pre><span class="line">public class SemaphoreCommand extends HystrixCommand&lt;String&gt; &#123;</span><br><span class="line"></span><br><span class="line">    CountDownLatch countDownLatch = new CountDownLatch(20);</span><br><span class="line"></span><br><span class="line">    private String name;</span><br><span class="line"></span><br><span class="line">    /**</span><br><span class="line">     * 信号量隔离，并发请求数为10</span><br><span class="line">     * @param name</span><br><span class="line">     */</span><br><span class="line">    public SemaphoreCommand(String name) &#123;</span><br><span class="line">        super(Setter</span><br><span class="line">                .withGroupKey(HystrixCommandGroupKey.Factory.asKey(&quot;semaphore&quot;))</span><br><span class="line">                .andCommandPropertiesDefaults(</span><br><span class="line">                        HystrixCommandProperties.Setter().withExecutionIsolationStrategy(</span><br><span class="line">                                HystrixCommandProperties.ExecutionIsolationStrategy.SEMAPHORE</span><br><span class="line">                        )</span><br><span class="line">                )</span><br><span class="line">        );</span><br><span class="line">        this.name = name;</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    @Override</span><br><span class="line">    protected String run() throws Exception &#123;</span><br><span class="line">        TimeUnit.MILLISECONDS.sleep(100);</span><br><span class="line">        return &quot;Hello &quot; + name + &quot;,current thread:&quot; + Thread.currentThread().getName();</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    @Override</span><br><span class="line">    protected String getFallback() &#123;</span><br><span class="line">        return &quot;【调用阻塞】：&quot; + Thread.currentThread().getName();</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    public static void main(String[] args) &#123;</span><br><span class="line">        SemaphoreCommand semaphoreCommand = new SemaphoreCommand(&quot;semaphore-command&quot;);</span><br><span class="line">        semaphoreCommand.testExecute();</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    public void testExecute() &#123;</span><br><span class="line">        for (int i = 0; i &lt; 20; i++) &#123;</span><br><span class="line">            new Thread(new Task(countDownLatch)).start();</span><br><span class="line">        &#125;</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    public class Task implements Runnable &#123;</span><br><span class="line"></span><br><span class="line">        private CountDownLatch countDownLatch;</span><br><span class="line"></span><br><span class="line">        public Task(CountDownLatch countDownLatch) &#123;</span><br><span class="line">            this.countDownLatch = countDownLatch;</span><br><span class="line">        &#125;</span><br><span class="line"></span><br><span class="line">        @Override</span><br><span class="line">        public void run() &#123;</span><br><span class="line">            countDownLatch.countDown();</span><br><span class="line">            try &#123;</span><br><span class="line">                countDownLatch.await();</span><br><span class="line">            &#125; catch (InterruptedException e) &#123;</span><br><span class="line">                e.printStackTrace();</span><br><span class="line">            &#125;</span><br><span class="line">            SemaphoreCommand semaphoreCommand = new SemaphoreCommand(&quot;semaphore-command&quot;);</span><br><span class="line">            System.out.println(semaphoreCommand.execute());</span><br><span class="line">        &#125;</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
</li>
</ol>
<h1 id="四、熔断降级"><a href="#四、熔断降级" class="headerlink" title="四、熔断降级"></a>四、熔断降级</h1><ol>
<li>模拟10s内发送20个失败的请求，触发熔断器开关打开</li>
<li>等待熔断器半打开，执行一个请求<figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br></pre></td><td class="code"><pre><span class="line">public class RequestErrorCommand extends HystrixCommand&lt;String&gt; &#123;</span><br><span class="line"></span><br><span class="line">    private String name;</span><br><span class="line"></span><br><span class="line">    private Integer count;</span><br><span class="line"></span><br><span class="line">    public RequestErrorCommand(String name, Integer count) &#123;</span><br><span class="line">        super(HystrixCommandGroupKey.Factory.asKey(&quot;RequestErrorCommand&quot;));</span><br><span class="line">        this.name = name;</span><br><span class="line">        this.count = count;</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    @Override</span><br><span class="line">    protected String run() throws Exception &#123;</span><br><span class="line">        if (count &lt; 20) &#123;</span><br><span class="line">            throw new RuntimeException(&quot;【模拟调用失败】&quot;);</span><br><span class="line">        &#125;</span><br><span class="line">        return &quot;Hello &quot; + name + &quot;,current thread:&quot; + Thread.currentThread().getName();</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    @Override</span><br><span class="line">    protected String getFallback() &#123;</span><br><span class="line">        return &quot;【调用服务阻塞】&quot;;</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    public static void main(String[] args) throws InterruptedException &#123;</span><br><span class="line">        for (int i = 0; i &lt; 25; i++) &#123;</span><br><span class="line">            Thread.sleep(500);</span><br><span class="line">            RequestErrorCommand requestErrorCommand = new RequestErrorCommand(&quot;error&quot;, i);</span><br><span class="line">            System.out.println(requestErrorCommand.execute() + &quot;======&gt;&quot; + i + &quot;===&gt;【熔断器是否打开】：&quot; + requestErrorCommand.isCircuitBreakerOpen());</span><br><span class="line">        &#125;</span><br><span class="line"></span><br><span class="line">        Thread.sleep(3000);</span><br><span class="line">        RequestErrorCommand requestErrorCommand = new RequestErrorCommand(&quot;error&quot;, 1000);</span><br><span class="line">        System.out.println(requestErrorCommand.execute());</span><br><span class="line">    &#125;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
</li>
</ol>
<h1 id="五、请求缓存"><a href="#五、请求缓存" class="headerlink" title="五、请求缓存"></a>五、请求缓存</h1><p>==注意==：请求缓存只针对同一个context下才有效<br><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br></pre></td><td class="code"><pre><span class="line">public class RequestCacheCommand extends HystrixCommand&lt;String&gt; &#123;</span><br><span class="line"></span><br><span class="line">    private Integer id;</span><br><span class="line"></span><br><span class="line">    public RequestCacheCommand(Integer id) &#123;</span><br><span class="line">        super(HystrixCommandGroupKey.Factory.asKey(&quot;request-cache&quot;));</span><br><span class="line">        this.id = id;</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    @Override</span><br><span class="line">    protected String run() throws Exception &#123;</span><br><span class="line">        return &quot;current thread &quot; + Thread.currentThread().getName() + &quot; execute &quot; + id;</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    @Override</span><br><span class="line">    protected String getCacheKey() &#123;</span><br><span class="line">        return String.valueOf(id);</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    public static void main(String[] args)&#123;</span><br><span class="line">        HystrixRequestContext context = HystrixRequestContext.initializeContext();</span><br><span class="line">        try &#123;</span><br><span class="line">            RequestCacheCommand command2a = new RequestCacheCommand(2);</span><br><span class="line">            RequestCacheCommand command2b = new RequestCacheCommand(2);</span><br><span class="line">            command2a.execute();</span><br><span class="line">            command2b.execute();</span><br><span class="line">            // isResponseFromCache判定是否是在缓存中获取结果</span><br><span class="line">            System.out.println(&quot;是否从缓存中读取结果：&quot; + command2a.isResponseFromCache());</span><br><span class="line">            System.out.println(&quot;是否从缓存中读取结果：&quot; + command2b.isResponseFromCache());</span><br><span class="line">        &#125; finally &#123;</span><br><span class="line">            context.shutdown();</span><br><span class="line">        &#125;</span><br><span class="line"></span><br><span class="line">        context = HystrixRequestContext.initializeContext();</span><br><span class="line">        try &#123;</span><br><span class="line">            RequestCacheCommand command3b = new RequestCacheCommand(2);</span><br><span class="line">            System.out.println(command3b.isResponseFromCache());</span><br><span class="line">        &#125; finally &#123;</span><br><span class="line">            context.shutdown();</span><br><span class="line">        &#125;</span><br><span class="line">    &#125;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure></p>
<h1 id="六、请求合并"><a href="#六、请求合并" class="headerlink" title="六、请求合并"></a>六、请求合并</h1><ol>
<li><p>定义实体</p>
<figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br></pre></td><td class="code"><pre><span class="line">@Data</span><br><span class="line">@Builder</span><br><span class="line">@NoArgsConstructor</span><br><span class="line">@AllArgsConstructor</span><br><span class="line">@ToString</span><br><span class="line">public class User &#123;</span><br><span class="line"></span><br><span class="line">    private Integer id;</span><br><span class="line"></span><br><span class="line">    private String name;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
</li>
<li><p>定义业务方法</p>
<figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br></pre></td><td class="code"><pre><span class="line">public class UserService &#123;</span><br><span class="line"></span><br><span class="line">    public List&lt;User&gt; listUser(List&lt;Integer&gt; userIdList) &#123;</span><br><span class="line">        System.out.println(&quot;【请求参数】：&quot; + userIdList);</span><br><span class="line">        List&lt;User&gt; userList = new ArrayList&lt;&gt;();</span><br><span class="line">        for (Integer userId : userIdList) &#123;</span><br><span class="line">            User user = User.builder()</span><br><span class="line">                    .id(userId)</span><br><span class="line">                    .name(&quot;测试&quot; + userId)</span><br><span class="line">                    .build();</span><br><span class="line">            userList.add(user);</span><br><span class="line">        &#125;</span><br><span class="line"></span><br><span class="line">        return userList;</span><br><span class="line">    &#125;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
</li>
<li><p>定义comand</p>
<figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br></pre></td><td class="code"><pre><span class="line">public class UserCommand extends HystrixCommand&lt;List&lt;User&gt;&gt; &#123;</span><br><span class="line"></span><br><span class="line">    private List&lt;Integer&gt; userIdList;</span><br><span class="line"></span><br><span class="line">    private UserService userService;</span><br><span class="line"></span><br><span class="line">    public UserCommand(List&lt;Integer&gt; userIdList, UserService userService) &#123;</span><br><span class="line">        super(HystrixCommandGroupKey.Factory.asKey(&quot;UserCommand&quot;));</span><br><span class="line">        this.userIdList = userIdList;</span><br><span class="line">        this.userService = userService;</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    @Override</span><br><span class="line">    protected List&lt;User&gt; run() throws Exception &#123;</span><br><span class="line">        List&lt;User&gt; userList = userService.listUser(userIdList);</span><br><span class="line">        System.out.println(userList);</span><br><span class="line">        return userList;</span><br><span class="line">    &#125;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
</li>
<li><p>定义基于请求范围内的请求合并</p>
<figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br></pre></td><td class="code"><pre><span class="line">public class UserCommandCollapser extends HystrixCollapser&lt;List&lt;User&gt;, User, Integer&gt; &#123;</span><br><span class="line"></span><br><span class="line">    private Integer userId;</span><br><span class="line"></span><br><span class="line">    private UserService userService;</span><br><span class="line"></span><br><span class="line">    public UserCommandCollapser(Integer userId, UserService userService) &#123;</span><br><span class="line">        super(Setter</span><br><span class="line">                .withCollapserKey(HystrixCollapserKey.Factory.asKey(&quot;UserCommandCollapser&quot;))</span><br><span class="line">                .andCollapserPropertiesDefaults(HystrixCollapserProperties.Setter().withTimerDelayInMilliseconds(100)));</span><br><span class="line">        this.userId = userId;</span><br><span class="line">        this.userService = userService;</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    @Override</span><br><span class="line">    public Integer getRequestArgument() &#123;</span><br><span class="line">        return userId;</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    @Override</span><br><span class="line">    protected HystrixCommand&lt;List&lt;User&gt;&gt; createCommand(Collection&lt;CollapsedRequest&lt;User, Integer&gt;&gt; collapsedRequests) &#123;</span><br><span class="line">        List&lt;Integer&gt; userIdList = new ArrayList&lt;&gt;(collapsedRequests.size());</span><br><span class="line">        userIdList.addAll(collapsedRequests.stream().map(CollapsedRequest::getArgument).collect(Collectors.toList()));</span><br><span class="line">        return new UserCommand(userIdList, userService);</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    @Override</span><br><span class="line">    protected void mapResponseToRequests(List&lt;User&gt; batchResponse, Collection&lt;CollapsedRequest&lt;User, Integer&gt;&gt; collapsedRequests) &#123;</span><br><span class="line">        int count = 0;</span><br><span class="line"></span><br><span class="line">        for (CollapsedRequest&lt;User, Integer&gt; collapsedRequest : collapsedRequests) &#123;</span><br><span class="line">            User user = batchResponse.get(count++);</span><br><span class="line">            collapsedRequest.setResponse(user);</span><br><span class="line">        &#125;</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    public static void main(String[] args) throws ExecutionException, InterruptedException &#123;</span><br><span class="line">        UserService userService = new UserService();</span><br><span class="line"></span><br><span class="line">        HystrixRequestContext context = HystrixRequestContext.initializeContext();</span><br><span class="line">        try &#123;</span><br><span class="line">            Future&lt;User&gt; f1 = new UserCommandCollapser(10001, userService).queue();</span><br><span class="line">            Future&lt;User&gt; f2 = new UserCommandCollapser(10002, userService).queue();</span><br><span class="line">            Future&lt;User&gt; f3 = new UserCommandCollapser(10003, userService).queue();</span><br><span class="line">            Future&lt;User&gt; f4 = new UserCommandCollapser(10004, userService).queue();</span><br><span class="line">            Future&lt;User&gt; f5 = new UserCommandCollapser(10005, userService).queue();</span><br><span class="line"></span><br><span class="line">            f1.get();</span><br><span class="line">            f2.get();</span><br><span class="line">            f3.get();</span><br><span class="line">            f4.get();</span><br><span class="line">            f5.get();</span><br><span class="line"></span><br><span class="line">            System.out.println(&quot;execute command size：&quot; + HystrixRequestLog.getCurrentRequest().getAllExecutedCommands().size());</span><br><span class="line">        &#125; finally &#123;</span><br><span class="line">            context.shutdown();</span><br><span class="line">        &#125;</span><br><span class="line">    &#125;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
</li>
<li><p>定义基于全局范围内的请求合并</p>
<figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br><span class="line">61</span><br><span class="line">62</span><br><span class="line">63</span><br><span class="line">64</span><br><span class="line">65</span><br><span class="line">66</span><br><span class="line">67</span><br><span class="line">68</span><br><span class="line">69</span><br><span class="line">70</span><br><span class="line">71</span><br><span class="line">72</span><br><span class="line">73</span><br><span class="line">74</span><br><span class="line">75</span><br><span class="line">76</span><br><span class="line">77</span><br><span class="line">78</span><br><span class="line">79</span><br><span class="line">80</span><br><span class="line">81</span><br><span class="line">82</span><br><span class="line">83</span><br><span class="line">84</span><br><span class="line">85</span><br><span class="line">86</span><br><span class="line">87</span><br><span class="line">88</span><br><span class="line">89</span><br><span class="line">90</span><br><span class="line">91</span><br><span class="line">92</span><br><span class="line">93</span><br><span class="line">94</span><br><span class="line">95</span><br><span class="line">96</span><br><span class="line">97</span><br><span class="line">98</span><br><span class="line">99</span><br><span class="line">100</span><br><span class="line">101</span><br><span class="line">102</span><br><span class="line">103</span><br><span class="line">104</span><br><span class="line">105</span><br><span class="line">106</span><br><span class="line">107</span><br><span class="line">108</span><br><span class="line">109</span><br><span class="line">110</span><br><span class="line">111</span><br><span class="line">112</span><br><span class="line">113</span><br><span class="line">114</span><br><span class="line">115</span><br><span class="line">116</span><br><span class="line">117</span><br><span class="line">118</span><br><span class="line">119</span><br><span class="line">120</span><br><span class="line">121</span><br><span class="line">122</span><br><span class="line">123</span><br><span class="line">124</span><br><span class="line">125</span><br><span class="line">126</span><br><span class="line">127</span><br><span class="line">128</span><br><span class="line">129</span><br><span class="line">130</span><br><span class="line">131</span><br><span class="line">132</span><br><span class="line">133</span><br><span class="line">134</span><br><span class="line">135</span><br><span class="line">136</span><br><span class="line">137</span><br><span class="line">138</span><br><span class="line">139</span><br><span class="line">140</span><br><span class="line">141</span><br><span class="line">142</span><br><span class="line">143</span><br><span class="line">144</span><br><span class="line">145</span><br><span class="line">146</span><br><span class="line">147</span><br><span class="line">148</span><br><span class="line">149</span><br><span class="line">150</span><br><span class="line">151</span><br><span class="line">152</span><br><span class="line">153</span><br><span class="line">154</span><br><span class="line">155</span><br><span class="line">156</span><br><span class="line">157</span><br><span class="line">158</span><br><span class="line">159</span><br><span class="line">160</span><br><span class="line">161</span><br><span class="line">162</span><br><span class="line">163</span><br><span class="line">164</span><br><span class="line">165</span><br></pre></td><td class="code"><pre><span class="line">public class UserCommandCollapser1 extends HystrixCollapser&lt;List&lt;User&gt;, User, Integer&gt; &#123;</span><br><span class="line"></span><br><span class="line">    private Integer userId;</span><br><span class="line"></span><br><span class="line">    private UserService userService;</span><br><span class="line"></span><br><span class="line">    public UserCommandCollapser1(Integer userId, UserService userService) &#123;</span><br><span class="line">        super(Setter</span><br><span class="line">                .withCollapserKey(HystrixCollapserKey.Factory.asKey(&quot;UserCommandCollapser&quot;))</span><br><span class="line">                .andCollapserPropertiesDefaults(HystrixCollapserProperties.Setter().withTimerDelayInMilliseconds(100))</span><br><span class="line">                .andScope(Scope.GLOBAL));</span><br><span class="line">        this.userId = userId;</span><br><span class="line">        this.userService = userService;</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    @Override</span><br><span class="line">    public Integer getRequestArgument() &#123;</span><br><span class="line">        return userId;</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    @Override</span><br><span class="line">    protected HystrixCommand&lt;List&lt;User&gt;&gt; createCommand(Collection&lt;CollapsedRequest&lt;User, Integer&gt;&gt; collapsedRequests) &#123;</span><br><span class="line">        List&lt;Integer&gt; userIdList = new ArrayList&lt;&gt;(collapsedRequests.size());</span><br><span class="line">        userIdList.addAll(collapsedRequests.stream().map(CollapsedRequest::getArgument).collect(Collectors.toList()));</span><br><span class="line">        return new UserCommand(userIdList, userService);</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    @Override</span><br><span class="line">    protected void mapResponseToRequests(List&lt;User&gt; batchResponse, Collection&lt;CollapsedRequest&lt;User, Integer&gt;&gt; collapsedRequests) &#123;</span><br><span class="line">        int count = 0;</span><br><span class="line"></span><br><span class="line">        for (CollapsedRequest&lt;User, Integer&gt; collapsedRequest : collapsedRequests) &#123;</span><br><span class="line">            User user = batchResponse.get(count++);</span><br><span class="line">            collapsedRequest.setResponse(user);</span><br><span class="line">        &#125;</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line"></span><br><span class="line">    public static void main(String[] args) throws ExecutionException, InterruptedException &#123;</span><br><span class="line">        UserService userService = new UserService();</span><br><span class="line">        Thread thread1 = new Thread(() -&gt; &#123;</span><br><span class="line">            try &#123;</span><br><span class="line">                test1(userService);</span><br><span class="line">            &#125; catch (ExecutionException e) &#123;</span><br><span class="line">                e.printStackTrace();</span><br><span class="line">            &#125; catch (InterruptedException e) &#123;</span><br><span class="line">                e.printStackTrace();</span><br><span class="line">            &#125;</span><br><span class="line">        &#125;);</span><br><span class="line"></span><br><span class="line">        Thread thread2 = new Thread(() -&gt; &#123;</span><br><span class="line">            try &#123;</span><br><span class="line">                test2(userService);</span><br><span class="line">            &#125; catch (ExecutionException e) &#123;</span><br><span class="line">                e.printStackTrace();</span><br><span class="line">            &#125; catch (InterruptedException e) &#123;</span><br><span class="line">                e.printStackTrace();</span><br><span class="line">            &#125;</span><br><span class="line">        &#125;);</span><br><span class="line"></span><br><span class="line">        Thread thread3 = new Thread(() -&gt; &#123;</span><br><span class="line">            try &#123;</span><br><span class="line">                test3(userService);</span><br><span class="line">            &#125; catch (ExecutionException e) &#123;</span><br><span class="line">                e.printStackTrace();</span><br><span class="line">            &#125; catch (InterruptedException e) &#123;</span><br><span class="line">                e.printStackTrace();</span><br><span class="line">            &#125;</span><br><span class="line">        &#125;);</span><br><span class="line"></span><br><span class="line">        Thread thread4 = new Thread(() -&gt; &#123;</span><br><span class="line">            try &#123;</span><br><span class="line">                test4(userService);</span><br><span class="line">            &#125; catch (ExecutionException e) &#123;</span><br><span class="line">                e.printStackTrace();</span><br><span class="line">            &#125; catch (InterruptedException e) &#123;</span><br><span class="line">                e.printStackTrace();</span><br><span class="line">            &#125;</span><br><span class="line">        &#125;);</span><br><span class="line"></span><br><span class="line">        Thread thread5 = new Thread(() -&gt; &#123;</span><br><span class="line">            try &#123;</span><br><span class="line">                test5(userService);</span><br><span class="line">            &#125; catch (ExecutionException e) &#123;</span><br><span class="line">                e.printStackTrace();</span><br><span class="line">            &#125; catch (InterruptedException e) &#123;</span><br><span class="line">                e.printStackTrace();</span><br><span class="line">            &#125;</span><br><span class="line">        &#125;);</span><br><span class="line"></span><br><span class="line">        thread1.start();</span><br><span class="line">        thread2.start();</span><br><span class="line">        thread3.start();</span><br><span class="line">        thread4.start();</span><br><span class="line">        thread5.start();</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    public static void test1(UserService userService) throws ExecutionException, InterruptedException &#123;</span><br><span class="line">        HystrixRequestContext context = HystrixRequestContext.initializeContext();</span><br><span class="line">        try &#123;</span><br><span class="line">            Future&lt;User&gt; f1 = new UserCommandCollapser1(10001, userService).queue();</span><br><span class="line"></span><br><span class="line">            System.out.println(&quot;【请求1】：&quot; + f1.get());</span><br><span class="line"></span><br><span class="line">            System.out.println(&quot;execute command size：&quot; + HystrixRequestLog.getCurrentRequest().getAllExecutedCommands().size());</span><br><span class="line">        &#125; finally &#123;</span><br><span class="line">            context.shutdown();</span><br><span class="line">        &#125;</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    public static void test2(UserService userService) throws ExecutionException, InterruptedException &#123;</span><br><span class="line">        HystrixRequestContext context = HystrixRequestContext.initializeContext();</span><br><span class="line">        try &#123;</span><br><span class="line">            Future&lt;User&gt; f2 = new UserCommandCollapser1(10002, userService).queue();</span><br><span class="line"></span><br><span class="line"></span><br><span class="line">            System.out.println(&quot;【请求2】：&quot; + f2.get());</span><br><span class="line"></span><br><span class="line">            System.out.println(&quot;execute command size：&quot; + HystrixRequestLog.getCurrentRequest().getAllExecutedCommands().size());</span><br><span class="line">        &#125; finally &#123;</span><br><span class="line">            context.shutdown();</span><br><span class="line">        &#125;</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    public static void test3(UserService userService) throws ExecutionException, InterruptedException &#123;</span><br><span class="line">        HystrixRequestContext context = HystrixRequestContext.initializeContext();</span><br><span class="line">        try &#123;</span><br><span class="line">            Future&lt;User&gt; f3 = new UserCommandCollapser1(10003, userService).queue();</span><br><span class="line"></span><br><span class="line"></span><br><span class="line">            System.out.println(&quot;【请求3】：&quot; + f3.get());</span><br><span class="line"></span><br><span class="line">            System.out.println(&quot;execute command size：&quot; + HystrixRequestLog.getCurrentRequest().getAllExecutedCommands().size());</span><br><span class="line">        &#125; finally &#123;</span><br><span class="line">            context.shutdown();</span><br><span class="line">        &#125;</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    public static void test4(UserService userService) throws ExecutionException, InterruptedException &#123;</span><br><span class="line">        HystrixRequestContext context = HystrixRequestContext.initializeContext();</span><br><span class="line">        try &#123;</span><br><span class="line">            Future&lt;User&gt; f4 = new UserCommandCollapser1(10004, userService).queue();</span><br><span class="line"></span><br><span class="line">            System.out.println(&quot;【请求4】：&quot; + f4.get());</span><br><span class="line"></span><br><span class="line">            System.out.println(&quot;execute command size：&quot; + HystrixRequestLog.getCurrentRequest().getAllExecutedCommands().size());</span><br><span class="line">        &#125; finally &#123;</span><br><span class="line">            context.shutdown();</span><br><span class="line">        &#125;</span><br><span class="line">    &#125;</span><br><span class="line"></span><br><span class="line">    public static void test5(UserService userService) throws ExecutionException, InterruptedException &#123;</span><br><span class="line">        HystrixRequestContext context = HystrixRequestContext.initializeContext();</span><br><span class="line">        try &#123;</span><br><span class="line">            Future&lt;User&gt; f5 = new UserCommandCollapser1(10005, userService).queue();</span><br><span class="line"></span><br><span class="line"></span><br><span class="line">            System.out.println(&quot;【请求5】：&quot; + f5.get());</span><br><span class="line"></span><br><span class="line">            System.out.println(&quot;execute command size：&quot; + HystrixRequestLog.getCurrentRequest().getAllExecutedCommands().size());</span><br><span class="line">        &#125; finally &#123;</span><br><span class="line">            context.shutdown();</span><br><span class="line">        &#125;</span><br><span class="line">    &#125;</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>
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              <div class="post-toc-content"><ol class="nav"><li class="nav-item nav-level-3"><a class="nav-link" href="#Hystrix简单使用、降级、熔断、请求缓存、请求合并示例"><span class="nav-number">1.</span> <span class="nav-text">Hystrix简单使用、降级、熔断、请求缓存、请求合并示例</span></a></li></ol></li></ol></li><li class="nav-item nav-level-1"><a class="nav-link" href="#一、简单使用"><span class="nav-number"></span> <span class="nav-text">一、简单使用</span></a></li><li class="nav-item nav-level-1"><a class="nav-link" href="#二、带有降级逻辑"><span class="nav-number"></span> <span class="nav-text">二、带有降级逻辑</span></a></li><li class="nav-item nav-level-1"><a class="nav-link" href="#三、模拟信号量隔离"><span class="nav-number"></span> <span class="nav-text">三、模拟信号量隔离</span></a></li><li class="nav-item nav-level-1"><a class="nav-link" href="#四、熔断降级"><span class="nav-number"></span> <span class="nav-text">四、熔断降级</span></a></li><li class="nav-item nav-level-1"><a class="nav-link" href="#五、请求缓存"><span class="nav-number"></span> <span class="nav-text">五、请求缓存</span></a></li><li class="nav-item nav-level-1"><a class="nav-link" href="#六、请求合并"><span class="nav-number"></span> <span class="nav-text">六、请求合并</span></a></div>
            

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